In order to utilize the electric power energy of a vehicle efficiently, an electric power supply system has been proposed, in which, when the electric power of a self vehicle is short, the electric power is received from the exterior of the vehicle, and when the electric power of a self vehicle has a surplus, the electric power is transmitted to the exterior of the vehicle. According to the description of JPA-2005-210843, when a surplus occurs in the remaining capacity of a battery as a result of collecting regeneration energies, for example, surplus electric power is transmitted from a vehicular power supply device to the exterior of the vehicle. Accordingly, the collected regeneration energy and the like are effectively utilized.
When the surplus electric power is transmitted to the exterior of the vehicle in this way, it suffices to determine a quantity of electric power transmission so that the self vehicle may not fall in electric power deficiency. In particular, in cases where the destination is set up, it is desirable to preserve a necessary electric power quantity to reach at least there and to transmit the remaining quantity to the exterior of the vehicle as surplus electric power.
However, the vehicular power supply device described in JP-A-2005-210843 is configured such that the quantity of collected regeneration energy is treated as surplus electric power, and no consideration is taken for a necessary electric power quantity for traveling to a destination. In this regard, it is possible to calculate the necessary electric power quantity for traveling to the destination, for example, using the mean electric power consumption of the self vehicle. However, it is difficult to expect sufficient accuracy in the calculation. Even if electric power consumption has been recorded in conjunction with the route traveled by the self vehicle, it is difficult to calculate a necessary electric power quantity with sufficient accuracy, in the case of traveling a new route which had not been traveled in the past.